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Technology: Computer brings cheap tricks to the screen

By BARRY FOX

Breathtaking special effects, like those that made the $100 million
Terminator 2: Judgment Day the most expensive film ever made, will in future
be cheaper and easier to create using a purpose-built British computer.
It comes from Quantel which has been making special effects equipment for
the TV and video industry since 1973. The Newbury-based company has now
built a system which plays the same tricks with cinema film.

Quantel’s video systems, known as Harry and Paintbox, store sequences
of TV pictures on a computer disc so that an operator with an electronic
pen and pressure-sensitive pad can manipulate and blend them. Most TV programmes
and commercials now use this technology for some of their sequences.

Meanwhile, the cinema film industry has to make do with optical techniques
developed before the First World War. To make Peter Pan fly over the countryside,
film editors hold one piece of film showing the countryside against another
piece of film of Peter Pan suspended on wires and copy the combined image
onto blank negative film.

For complicated effects, such as battles in space, up to 10 images of
models, backgrounds and actors are copied onto the same negative. One mistake
can spoil weeks of work.

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As an electronic alternative, Quantel has developed a system called
Digital Opticals for Movies, or Domino, which includes a computer workstation
and a wide, high-definition monitor. A length of movie film is run through
a scanner which converts it into a series of digital electronic images which
are stored on computer hard discs. Each image is made up of 2000 picture
lines, each with 2900 individual picture points or ‘pixels’. This is twice
the resolution of high-definition TV and at least twice that of processed
35-millimetre move film, as the grains in the film’s emulsion are much larger
than the digitised pixels.

Domino can display up to 30 pictures a second, but needs specially adapted
hardware to do so because so much digital information is needed to make
up each image that it is very hard to read it off the disc fast enough.
Previous high-resolution picture processors have taken many seconds to display
each picture, and many minutes to alter it.

The information is therefore divided between eight hard disc drives,
each with several recording heads. The discs have a combined capacity of
16 gigabytes, which is enough to hold up to one-and-a-half minutes of moving
images. Information streams from the heads and discs at a combined rate
of over 100 megabytes per second, around 100 times the maximum reading speed
of a personal computer. Domino then processes it at a rate of more than
100 million calculations a second. The result on screen is smooth cinema
motion.

To create a special effect, the operator works on one image first and
then leaves the computer to mimic this work in subsequent images. Film makers
can use an electronic airbrush to remove TV aerials, telephone wires and
road signs which make modern locations unusable for period dramas.

It is equally easy to get rid of scratches or blemishes from film, put
moving clouds into a clear sky, turn a road into a rippling river, or graft
moving images of action scenes into an otherwise blank window frame, with
perspective varied to match the viewing angle.

Once all the process work has been done, the digital signal is fed to
a high-resolution film recorder which transfers the pictures back onto movie
film again.

Quantel is aiming to have systems ready for sale in the second half
of 1992, at a price likely to exceed a million pounds.